PT Journal AU LHCb Collaboration (Aaij, Rea Jaimes Elles, SJ Jashal, BK Martinez-Vidal, F Oyanguren, A Rebollo De Miguel, M Remon Alepuz, C Ruiz Vidal, J Sanderswood, I TI Measurement of τL using the Bs0 →J/ψη decay mode SO European Physical Journal C JI Eur. Phys. J. C PY 2023 BP 629 - 13pp VL 83 IS 7 DI 10.1140/epjc/s10052-023-11634-4 LA English AB Using a proton-proton collision data sample collected by the LHCb detector and corresponding to an integrated luminosity of 5.7 fb(-1), the lifetime of the light B-s(0) mass eigenstate, tau(L), is measured using the B-s(0) -> J/psi eta decay mode to be tau(L) = 1.445 +/- 0.016(stat) +/- 0.008(syst) ps. A combination of this result with a previous LHCb analysis using an independent dataset corresponding to 3 fb(-1) of integrated luminosity gives tau(L) = 1.452 +/- 0.014 +/- 0.007 +/- 0.002 ps, where the first uncertainty is statistical, the second due to the uncorrelated part of the systematic uncertainty and the third due to the correlated part of the systematic uncertainty. ER